Rig mats, which are also known as rig pads and road mats, have been used, for example, for construction roadways, camp mats, and drilling rig platforms on surfaces such as Arctic tundra, in order to provide a temporary rigid surface on which equipment such as motor vehicles can operate. Rig mats may assist in reducing damage to the softer surface below, and may prevent motor vehicles or other objects from becoming bogged down. They can also prevent the softer surface from thawing when the ambient air temperatures are above freezing, thereby retaining the integrity of the rigid surface for supporting loads placed thereon. The service of rig mats can be severe including the support of heavy loads including dynamic loads of wheeled and tracked vehicular traffic.
Conventional rig mats have been constructed with generally rectangular steel frame supporting wooden platforms within the frames for example. Some next generation rig mats utilize a composite material for the platform. Rig mats tend to be made of interconnectable panels, so that the panels are readily transported, and used and reused for temporary surfaces of various desired dimensions.
Generally rig mats do not provide any substantial thermal or reflective insulation value. More contemporary composite mats can have a core filled with insulating foam to provide a thermal barrier. In such a construction a top and bottom sheet of fibrous reinforcing material (FRP) is attached to an insulating material core. Insulated rig mats were introduced with the objective of keeping the ground frozen longer so as to keep the platform in place for a longer duration, thus increasing the useful life. With the high daily expense of drilling rigs, any increase in a drilling season results in significant benefits.
Arrangements which require interconnected panels, even with an insulating core, have inherent problems due to gaps, both physical gaps and increased thermal conductivity, caused by the structural interconnecting points between panels, defeating the insulation provided by the foam filled cores. There are also problems with effectively bonding foam to the skins of an insulated core which reduces the shear strength of the structure. Further, the physical gaps between panels are pathways for spills to the ground, substantially any spill being undesirable. Water and other undesirable fluids can seep through such gaps and contaminate the ground below the rig mat. When used in the Arctic the rig mats are generally placed over a bed of gravel which is typically remediated to ensure any spills, whether documented or not, are treated. The remediation itself comes with an environmental cost for equipment, consumables and fuel. One form of remediation is to steam clean the gravel after each drilling operation which involves transporting the gravel to a steam cleaning plant which is a cumbersome task in the Arctic and other remote areas typical of drilling operations.
It is known to form temporary surfaces of various desired dimensions by interconnecting rig mat panels using connectors such as complementary L-shaped appendages or connectors described in US Patent Application Publication No. 2009/0297266 to Stasiewich et al. The connectors are thermal conductors and are not leakproof.
There is a need for a rig mat which in addition to providing a rigid surface, minimizes leak and thermal issues.